function mse = meanSquaredError(x, y, parameter)
% Mean squared error between a straight line and data pairs.
%
% Arguments: x, vector of the input values
%            y, vector of the corresponding measured output values
%            parameter, vector containing slope and intercept 
%                       as the 1st and 2nd element, respectively. 
%
% Returns:   mse, the mean-squared-error.

  mse = mean((y - x * parameter(1) - parameter(2)).^2);
end